Plastics, such as polyolefins, are useful in many applications such as in fabrication of automobile parts and accessories. Such plastics offer advantages over other types of materials, such as metals like aluminum, for automobile parts and accessories. For example, these materials are less dense than metals, which lowers the overall weight of an automobile and increase vehicle fuel efficiency. Such materials are also more flexible and less expensive than metals. Typically, plastic automobile parts and accessories are painted to achieve a desired finish and appearance as well as to protect the part or accessories from weathering conditions such as sunlight, moisture, heat and cold.
However, the direct application of automotive paint systems to such plastic automobile parts and accessories has drawbacks, including an inadequate adherence of the paint to the parts or accessories. Such direct application may also lead to defects in the paint system, such as fish eyes, orange peel, cratering or cracking.
To circumvent the drawbacks associated with direct paint application to a plastic automobile part or accessory, an adhesion-promoting coating may be disposed on the automobile part or accessory prior to the application of paint. For example, U.S. Pat. No. 6,297,312, hereby incorporated in its entirety, discloses waterborne coating composition comprising a halogenated polyolefin, an anionic polyurethane, a coalescent agent, an anionic surfactant and a wetting agent. Such waterborne coating composition can be applied to a plastic surface, such as a thermoplastic polyolefin (TPO) surface, to facilitate adhesion of a paint system thereon. However, these waterborne coating compositions take about a week to cure under ambient conditions. The waterborne coating composition can be more quickly cured if heated to high temperatures, such as about 160° F.
As another example, U.S. Published Patent Application 2008/0255273, hereby incorporated in its entirety, discloses a waterborne coating composition comprising a polymer for forming a polymer matrix having carboxylate functionality and nano-scale zinc oxide particles dispersed in the polymer. Such waterborne coating composition can be applied to substrates such as glass, metal, polymeric substrates, e.g. polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyvinyl butyral (PVB), polyamide (PA), polyesters, polyamides, epoxy, polyurethanes, and siloxanes, wood, cotton, linen, wool, textiles, nonwovens, among other suitable substrates and combinations thereof. However, these waterborne coating compositions also take about a week to cure under ambient conditions.
Generally, waterborne coating compositions tend to produce coatings that do not display suitable adhesion of solventborne paint systems. Similarly, solventborne coating compositions tend to produce coatings that do not display suitable adhesion of waterborne paint systems. Such coating compositions have a limited compatibility with a large segment of the paint market.
Thus, there is a need in the art for a coating that promotes adequate adhesion of paint to a plastic automobile part or accessory as well as for a coating that is compatible with solventborne and waterborne paint systems. There is also a need for a coating that rapidly dries, promotes enhanced durability of the paint and promotes a desired finished appearance.